Human normal immunoglobulin (HNI) for use in the prevention and treatment of a number of infectious diseases was introduced in the late 1940's. HNI prepared by the cold ethanol fractionation method according to Cohn & Oncley (Cohn E., et al., (1946), J Am Chem Soc, 68, 459-475), (Oncley et al., (1949), J Am Chem Soc, 71, 541-550) and subsequently also by the modification made by Kistler and Nitschmann (Kistler P and Nitschmann HS, (1952), Vox Sang, 7, 414-424) proved to be both efficient and safe against the transmission of virus infection when administered subcutaneously or intramuscularly.
Congenital or acquired total or partial lack of immunoglobulin (primary and secondary immunodeficiency syndrome, respectively) manifests itself through frequent ordinary and serious infections, especially of a bacterial nature. The prevention of such infections was previously achieved by repeated intramuscular or subcutaneous injections of large amounts of HNI for up to several times a week as a life-lasting treatment, which is very painful when the medicament is given intramuscularly.
In the early sixties, administration of HNI by the intravenous route was therefore attempted. Trials showed that about 5% of healthy volunteers and about 95% of patients with an immunoglobulin deficiency developed immediate adverse effects varying from dyspnoea to circulatory shock and being of such serious nature that the intravenous administration of HNI had to be abandoned.
The reason for the adverse effects mentioned above turned out to be aggregates of immunoglobulins which, among other effects, strongly activated the complement system. This was in particular seen in patients lacking immunoglobulins. Especially serious adverse effects of an anaphylactic nature could be seen in patients who developed antibodies to IgA. Consequently, methods of avoiding aggregate formation and/or eliminating these aggregates during the preparation process were developed, and some twenty years ago the first generation of an immunoglobulin for intravenous administration (IVIG) was tested and found suitable.
The original purpose of an IVIG was to alleviate infectious episodes in patients with a congenital or acquired total or partial lack of immunoglobulins and to eliminate discomfort in connection with the administration of HNI. Another advantage of IVIG is that large doses of immunoglobulin can be given within a short time, and by this it is possible to obtain sufficiently high blood concentrations very quickly. Especially when treating serious bacterial infections it is of importance to establish high concentrations at sites of infections quickly.
In recent years, IVIG has furthermore proved to be efficient in other serious diseases, the treatment of which can otherwise be difficult, e.g. haemorrhages caused by the disappearance of the blood platelets on an immunological basis, idiopathic thrombocytopenic purpura (ITP), in some rare diseases such as Kawasaki's syndrome and a number of autoimmune diseases such as polyradiculitis (Guillain Barre's syndrome). Other diseases the treatment of which has been difficult to the present day are currently being subjected to clinical trials with IVIG. The mechanism of action in these diseases has only partly been clarified. The effect is supposed to be related to so-called immunomodulating properties of IgG, e.g. a blockage of Fc.gamma.-receptors on phagocytic cells, increased metabolism of IgG, downregulation of the production of cytokines, and interference with a supposed network of idiotypes/anti-idiotypes, especially relevant for the neutralization of autoimmune reactivity.
The first generation of IVIG was prepared by pepsin cleavage of the starting material (Cohn fraction II), the purpose of the cleavage being removal of immunoglobulin aggregates. No column chromatography steps were included in the process. The product had to be freeze-dried in order to remain stable for a reasonable period of time and was dissolved immediately prior to use.
The starting material for the IVIG was HNI which had proved to be safe with respect to the transmission of viruses when used for intramuscular injection. Hence, IVIG was considered to be just as safe. After several years of clinical use, however, IVIG products from some manufacturers were surprisingly shown to cause transfer of hepatitis C virus infection.
Studies to elucidate the fate of viruses during the production of HNI showed that the removal of virus in the fractionation process from plasma to HNI is modest. The safety of HNI for intramuscular use is likely to be due to the fact that it contains protective immunoglobulins. In combination with the modest volume injected and the intramuscular route of administration, these protective immunoglobulins can neutralize and render common viruses in plasma non-infectious. Especially when large doses of immunoglobulin are given intravenously, virus infections may occur as demonstrated in the early 1990's. Therefore, it was recognized that the production processes should comprise one or more well-defined virus-inactivation and/or removal steps.
A second generation of IVIG based on uncleaved and unmodified immunoglobulin molecules with low anticomplementary activity and higher stability was introduced in the mid-eighties, but still in the form of a freeze-dried product. This IVIG was purified by several chromatography steps. Products of that kind presently dominate the market for IVIG. The first and second generations of IVIG thus appear as freeze-dried powders which are dissolved immediately prior to use.
Dissolution of freeze-dried IVIG is slow (up to 30 minutes for one vial). Several portions often have to be dissolved for one patient. As it is of high priority for the users to have an IVIG in a solution ready for use, liquid products have been introduced on the market. More importantly, there is still a need for improvement of the production process in order to obtain a highly purified, stable and fully native IVIG preparation with higher clinical efficacy and less adverse drug reactions. A further developed and improved process for purifying IgG from crude plasma or a plasma protein fraction for a virus-safe, liquid IVIG product is thus needed. Finally, the process should be designed in such a way that it can be used in a large scale production.
The purification process described in the present application leads to a liquid immunoglobulin product for intravenous administration which can be characterized as a highly purified, fully native, biologically active, double virus-inactivated, and stable new generation of IVIG, which does not contain any detergent, polyethylene glycol (PEG) or albumin as a stabilizer.